This invention relates to methods and systems for communicating high rate data to customers in satellite-based communications networks.
A number of applications continue to drive the need for high-speed data transport. Industry specific examples include remote film editing, medical image transport, and financial service data consolidation and backup. Business communications and training needs further accelerate information transfer needs across all sectors. As business, government and educational institutions disseminate more information, greater importance is attached to data transfer. In this environment, reliable, high-speed video and data transport becomes even more critical.
Furthermore, a tremendous growth in Internet traffic has caused a strain on the capacity of telephony networks. Network shortcomings include network outages, insufficient access bandwidth, and insufficient internode bandwidth. Currently, providers need to make significant investments, as well as experience installation delays, to upgrade network infrastructure, yet they cannot pass the costs on to the end users.
Corporate LANs/WANs also generate an insatiable demand for higher bandwidth. The demand for bandwidth goes up as more and more users are connected. The users, in turn, demand more services and improved network speed. Personal computers are being used to process not only text, but graphics and video as well, all on networks that are increasingly global. Widespread implementation of corporate intranets and extranets further drive the move to increased bandwidth applications. High-speed networking is also driven by the growth of video distribution, client/server technology, decentralized systems, increased processing power and developments in storage capacity.
Thus, it is important to relieve congestion among the heavily used communications links in high-density areas and to bring such service to isolated rural areas which have not been able to participate fully in the communications world. While existing satellite systems offer ubiquitous service, they do not offer direct connection to the end user at moderate to high data rates. Existing Fixed Satellite Service (FSS) systems employ wide channel bandwidths and relatively large beamwidths making them more suited to point-to-point trunking service rather than to end user connectivity. The wide area coverage, limited Equivalent Isotropically Radiated Power (EIRP), and constrained flexibility of these systems makes any attempt to serve many small users both inefficient and costly.
The emerging cellular type satellite services serve a very large number of potential subscribers but only at very low data rates. The on-board processing and packet-switched nature of their signal structure severely limits the practical user data rates that can be accommodated within the technology limitations of the processor. Thus, there exists a need for a satellite communications system that serves the demand for high data rate business users including the high-end individual as well as small business users that demand direct and affordable connection.
It would therefore be desirable to provide a satellite-based communications network providing reliable high data rate communications service to customers throughout the world while maintaining flexibility to reconfigure the beam patterns often to tailor the beam pattern according to user needs.
In carrying out the above features, and advantages of the present invention, a satellite-based communications network provides a plurality of communications satellites each having uplink and downlink antennas capable of receiving and transmitting a plurality of signals utilizing a plurality of beams having fixed spot beams and scanned spot beams to a plurality of spot coverage areas and a plurality of scanned spot areas respectively at a predetermined range of frequencies. The plurality of satellites each have receiving and transmitting beam forming networks coupled to the uplink and downlink antennas respectively. The antennas have adjacent reconfigurable receiving and transmitting antenna elements. A controller located on the satellite is coupled to said beam forming network, the controller selecting either a fixed spot beam or a scanned spot beam.
One advantage of the invention is that the satellite system allows the use of both fixed and scanned spot beams from the same satellite and same antenna. This is important in high frequency applications such as those in V-band because the beams in high frequency bands generate narrow beams. Thus, blanket coverage for large land areas such as the continental United States (CONUS) is difficult without an inordinate number of satellite beams. The present invention allows fixed coverage over high traffic area while allowing scanned beams to be quickly moved between areas not requiring a dedicated fixed beam.
The above object and other objects, features and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.